repair the rad of coarse,
the *engine* coolant temp sensor would be a consideration,
http://www.autozone.com/autozone/rep...1ccbed#hd1-1-3
might pull codes first. not all codes stored prompt a light.
all you need is a jumper wire and your keys to pull codes on this. have the light blink,
http://www.autozone.com/autozone/rep...1ccc63#hd1-1-1
code chart,
http://www.autozone.com/autozone/rep...00c152801ccc73
consider, she might be in limp mode now. so do reset the ecu after pulling an addressing any code. pull 15 amp EFI main fuse. 30 secs. key off.
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a leaky head/gasket might cause this as well, coming off cold start.
sounds like you're going that direction next.
outward signs, they can be bad w/o evidence of fluid cross contamination, puffing white smoke, or backfiring.